Can quantitative diffusion-weighted MR imaging differentiate benign and malignant cold thyroid nodules? Initial results in 25 patients.
OBJECTIVE
The characterization of cold nodules of the thyroid gland is mandatory because approximately 20% of these nodules are of malignant origin. The purpose of this study was to evaluate the distinction of cold thyroid nodules by using quantitative diffusion-weighted MR imaging (DWI).


METHODS
In 25 patients with cold nodules on scintigraphy and suggestive findings at fine-needle aspiration, thyroid carcinoma was suggested. In these patients, cold nodules and the normal parenchyma of the contralateral thyroid lobe were prospectively investigated with quantitative DWI (echo-planar imaging sequence; maximum b-value, 800 s/mm(2)) before surgery. The differences in the mean apparent diffusion coefficient (ADC) values in benign and malignant nodules were tested by using a Mann-Whitney U test.


RESULTS
Histologically, there were 20 carcinomas with a minimum size of 8 mm and 5 adenomas. The mean ADC values (in 10(-3) mm(2)/s) differed significantly among carcinoma, adenoma, and normal parenchyma (P < .05). The ranges (95% confidence interval) of the ADC values for carcinoma (2.43-3.037), adenoma (1.626-2.233), and normal parenchyma (1.253-1.602) showed no overlap. When an ADC value of 2.25 or higher was used for predicting malignancy, the highest accuracy of 88%, with 85% sensitivity and 100% specificity, was obtained.


CONCLUSIONS
Quantitative DWI seems to be a feasible tool with which to differentiate thyroid carcinomas from adenomas; however, further studies are required including larger numbers of patients to confirm our results.
Schueller-Weidekamm
C
C
Department of Diagnostic Radiology, Medical University of Vienna, Vienna, Austria. claudia.schueller-weidekamm@meduniwien.ac.at
Kaserer
K
K
Schueller
G
G
Scheuba
C
C
Ringl
H
H
Weber
M
M
Czerny
C
C
Herneth
A M
AM
D018263:Adenocarcinoma, Follicular / Q000175:diagnosis; D000236:Adenoma / Q000175:diagnosis*; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002291:Carcinoma, Papillary / Q000175:diagnosis; D003937:Diagnosis, Differential; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods* / Q000592:standards; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009369:Neoplasms / Q000175:diagnosis*; D010865:Pilot Projects; D011446:Prospective Studies; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013964:Thyroid Neoplasms / Q000175:diagnosis*; D016606:Thyroid Nodule / Q000175:diagnosis*